Charles e



(No Model.)

O. E. SORIBNER.

MULTIPLE SWITCH BOARD TESTING APPARATUS. No. 384,644. Patented June 19, 1888.

"Minn STATES PATE T OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

MULTIPLE SWITCH-BOARD TESTING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 38 L644 dated June 19, 1888.

Application filed December 27, 1884. Serial No. 151,362. (No model.)

To all whom it nmy concern.-

- Be it known that I, CHARLES E. SORIBNER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful imobject is to provide means for testing to deter-' mine whether the line of a subscriber wanted is engaged. To accomplish this, -I take advantage of the well-knownlaw that condensers are conductors of telephonic or voice currents, but when placed in circuit with abattery after the first impulse no current can traverse th circuit.

My invention consists in including a condenser in the circuit with the telephone at the different subscribers stations and in providing a test-battery and signal-instrument at the central oflice and switching apparatus for connecting said battery with the different telephone-lines, whereby it may be determined whether the condenser of any given line is included in the circuit, and thereby'enable the operator to determine whether the telephone of the given line is on or off the hool:that is,

to determine whether the line is in use.

My invention is illustrated in the accompanying drawing, in which A and B, respectively, represent sections of two multiple switch-boards at the central office of a telephone-exchange.

C and D representtwo subscribersstations.

The circuit of the subscribers station C may be traced, as shown, by theline a to the spring of the spring-j ack b on board B,and from thence by wire a to the-spring of the springjackcon board A, and thence by wire a through the annunciator d to ground.

Station D is connected by line 6 with the switches f 9 upon the switch-boards, as shown. At station C, I have shown the telephone and bell in separate branch circuits. At station D, I have shown the telephone and bell connected one'after the other in the telephone-line, with means for shunting oneinstrument or the other by means of the apparatus described and claimed in Patent No. 283,927, granted me August 28, 1883.

The telephone-line e of station D is shown open at central office. When the telephonelines are thus left open, the Firman system of calling the central office, which consists of independent lines, is used.

I have shown one of the lines open at the central office and the other line closed through an annunciator, and at stations C and D, I have shown different circuits in order that it may be seen that my invention is not limited to any of the known systems ofconnecting the wires either at the central office or at the subscribers stations. As shown at station 0, the telephone is removed from the switch, and the circuitis thus connected through the telephone and thence through the condenser h to ground,

circuit of said battery may be closed to the switch of any line upon the multiple board A. Similar apparatus may'be provided at each board.

The telephone-line of each subscriber eX- tends from the switch at his station to a spring jack or switch upon the switch-board at the central oflice. If the telephone is removed from the switch at any subscribers station, the condenser will thereby be brought into the circuit. connects the battery to the line, the circuit will be found open at the condenser, and the signal-instrument will not be operated. If, on the other hand, the telephone is on the In this position, when the operator switch and the circuit of the line is closed through the bell directly to ground, the battery at the central office when connected to the line will find circuit to ground at the sub scribersstation. If the battery finds circuit,

the signal-instrument or sounder 70 will be en- 10o ergized, and the operator will know by the movement of the sounder that the telephone is hung on the switch at the terminal or subscribers station.

The closing of the sounder It, or whatever the signal-instru1nent may be, at the central office will thus indicate to the operator at the central oflice that the line is not being used by the subscriber. On the other hand, if the signal-instrument is not affected when the battery is closed to any given line, the operator will know that the telephone of the line is off the hook and the circuit of the battery cut off by the condenser. Thus when the signal-instrument indicates that the condenser is in circuit the operator will conclude that the line with which he has connected the battery is busy. Suppose the plug in at board B removed from the switch, so that the wires a a will be connected together through said switch. Suppose, now, that the operator at board A wishes to determine whether the telephone at station C is on the switch. By inserting the plug 11, as shown, in the switch of theline at his board and depressing the key 0, the circuit of battery 2 may be closed to said plug a, and thence through the medium of the switch to wire a, and thence the circuit may be traced to station 0, and thence through the telephone to the condenser 71. The battery-circuit being thus open at the condenser, no indication will be made by the signal-instrument k, and this will be notice to the operator that the condenser It is in the circuit, and hence that the the telephone is oil the hook. If, however, the telephone were hung on the hook, the line a would be connected through the bell directly to ground, and the battery Z accordingly would find circuit and operate the signalinstrunlent 7;, thus notifying the operator that the condenser h was out of the circuit, and hence that the telephone was on the hook. It will thus be seen that the operator at any switch-board may determine the position of the switch at any subscribers station.

Any form of telephone switch may be used at the subscribers stations. I have shown and described the gravity-switch, which is most commonlyin use, and which is so arranged that when the telephone is hung up the circuit will be directed through the bell. On the other hand, when the telephone is removed from the switch the position of the switch is changed, so as to cut out the bell and bring the telephone into circuit.

There are several other well-known forms of switches, among which I would mention those shown in myPatents No. 218,671, granted October 25, 1881.; No. 271,280, granted Janu cry 30, 1883, and No. 287,873, granted November 5, 1883, and also patent to George M. Phelps, No. 222,20l,granted December 2,1879.

I claim as my invention and desire to secure by Letters Patent 1. The combination, with the multiple switchboards of a telephoneexchange, of telephonelines connected therewith and each extending to a subscribers station, a condenser permanently connected in the branch wire containing the telephone between the telephone and ground at each subsoribers station, a telephone-switch at each subscrihers station for bringing the telephone and condenser into the circuit of the line when the telephone is removed from the switch-lever, a battery and Signaling instrument or sounder at the different switch-boards at the central office, and switching apparatus, whereby it may be detcrmined at any of the boards whether the in a ground-circuit at one ofthe switch-boards,

and switching apparatus for connecting said ground-circuit with said telephoneline at the switch of said board, whereby it may be determined whether the line is open at the spring-jack of said line at any other of the boards, substantially as described.

3. The combination,with the bell,telephoneswitch, and telephone atasubscribers station, of a condenser included in the branch of the switch which includes the telephone, the telephone-line permanently connected with the switch-lever and extending through a springjack on each of two or more multiple switchboards at the subscribers station, a sounder and batteryin a nor1nally-open groundcircuit at each of the switch-boards, and switching ICC 

